This invention relates to a forging apparatus, or apparatus for causing plastic deformation of metals, usually at elevated temperatures, into desired shapes by compressive forces exerted through dies, and more specifically to such a forging apparatus of the closed die variety.
Forging machines in general may be classified into open die and closed die designs depending upon the type of tooling employed and the way the required compressive forces are applied to the workpiece. In an open die machine the workpiece is placed between the two dies and squeezed so that the metal flows to take up the form in the dies. A certain amount of flash is unavoidable as the die faces do not come into contact until forging is completed. Closed dies, on the other hand, have their faces in contact with each other, completely enclosing the workpiece, before forging begins. The plastic deformation of the metal is achieved by means of a punch or punches that enter the die cavity from the top, bottom or side dependant upon the configuration of the desired component. Flash is very much less than with open dies because the die faces are in contact before forging begins.
In conventional closed die forging machines, however, difficulties have been encountered in positively holding the dies closed, during the forging of the confined metal by the punch or punches, with minimal exertion of power on the top die. Additional difficulties manifest themselves in connection with machines incorporating a side punch or punches together with an associated actuating mechanism or mechanisms for horizontally moving the punch or punches into and out of the die cavity. Powered by the same ram as the top die, the side punch actuating mechanisms must be so designed as to cause the side punch to effectively deform the metal with as small power requirement as possible.